/* -*- mode: C -*-  */
/* 
   IGraph library.
   Copyright (C) 2011-2012  Gabor Csardi <csardi.gabor@gmail.com>
   334 Harvard st, Cambridge, MA 02139, USA
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 
   02110-1301 USA

*/

#include <igraph.h>

int comp(void *extra, const void *a, const void *b) {
  igraph_vector_t *v=(igraph_vector_t*) extra;
  int *aa=(int*) a;
  int *bb=(int*) b;
  igraph_real_t aaa=VECTOR(*v)[*aa];
  igraph_real_t bbb=VECTOR(*v)[*bb];
  
  if (aaa < bbb) { 
    return -1;
  } else if (aaa > bbb) { 
    return 1;
  }
  
  return 0;
}

int main() {
  const int len=100;
  igraph_vector_t v;
  igraph_vector_int_t idx;
  int i;
  
  igraph_rng_seed(igraph_rng_default(), 42);
  igraph_vector_init(&v, len);
  igraph_vector_int_init(&idx, len);
  for (i=0; i<len; i++) {
    VECTOR(v)[i] = i;
    VECTOR(idx)[i] = i;
  }
  igraph_vector_shuffle(&v);

  igraph_qsort_r(VECTOR(idx), len, sizeof(VECTOR(idx)[0]), (void*) &v, comp);

  for (i=0; i<len; i++) { 
    printf("%g ", VECTOR(v)[ VECTOR(idx)[i] ]);
  }
  printf("\n");
  
  igraph_vector_int_destroy(&idx);
  igraph_vector_destroy(&v);

  return 0;
}
